1. Field of the Invention
The present general inventive concept relates to a toner usable with electrophotography and a method of preparing the same.
2. Description of the Related Art
In electrophotographic processes or electrostatic recording processes, a developer used to shape an electrostatic image or an electrostatic latent image can be classified as a two- component developer formed of toner and carrier particles, or a one-component developer formed of only toner. The one-component developer can be classified as a magnetic one-component developer or a nonmagnetic one-component developer. Fluidizing agents, such as colloidal silica, are often added to the nonmagnetic one-component developer to increase a fluidity of the toner. Typically, coloring particles obtained by dispersing a pigment, such as carbon black, or other additives in a binding resin are used as the toner.
Methods of preparing toner include pulverization and polymerization. In the pulverization method, the toner is obtained by melting and mixing synthetic resins with pigments and, if required, other additives. After the melting and mixing, the toner is obtained by pulverizing the mixture and sorting particles until particles of a desired size are obtained. In the polymerization method, a polymerizable monomer composition is manufactured by uniformly dissolving or dispersing various additives, such as a pigment, a polymerization initiator and, if required, a cross-linking agent and an antistatic agent in a polymerizable monomer. Then, the polymerizable monomer composition is dispersed in an aqueous dispersive medium, which includes a dispersion stabilizer by using an agitator to shape minute liquid droplet particles. Subsequently, a temperature of the aqueous dispersive medium is increased and suspension polymerization is performed to obtain polymerized toner having coloring polymer particles of a desired size.
In an image forming apparatus, such as an electrophotographic apparatus or an electrostatic recording apparatus, an image is formed by exposing an image on a uniformly charged photoreceptor to form an electrostatic latent image thereon, attaching toner to the electrostatic latent image to form a toner image, transferring the toner image onto a transfer medium, such as transfer paper, and then fixing the toner image onto the transfer medium by using any of a variety of methods, including heating, pressurizing, and solvent steaming. In some fixing processes, the transfer medium having the toner image disposed thereon passes through fixing rollers and pressing rollers and the toner image is fused to the transfer medium by heating and pressing.
Images formed by an image forming apparatus, such as an electrophotocopier, should satisfy requirements of high precision and accuracy. Conventionally, toner used in an image forming apparatus is typically obtained by the pulverization method. In the pulverization method, color particles having a large range of sizes are formed. Therefore, to obtain satisfactory developing properties, there is a need to sort the color particles obtained through the pulverization method according to size so as to reduce a particle size distribution. However, it is difficult to precisely control the particle size and the particle size distribution by using a conventional mixing/pulverizing process in the manufacture of toner that is suitable for an electrophotographic process or an electrostatic recording process. Also, when preparing a fine- particle-sized toner, the toner preparation yield is adversely affected by the sorting process. In addition, there are limits to a change/adjustment of a toner design to obtain desirable charging and fixing properties. Accordingly, polymerized toner, wherein size of the toner particles are easy to control and which do not need to undergo a complex manufacturing process, such as sorting, have been highlighted recently.
When toner is prepared through the polymerization method, polymerized toner having a desired particle size and particle size distribution may be obtained without pulverizing or sorting. However, even with polymerized toner, there are still demands for excellent print performance and high image quality when printing, and for physical properties of the toner, including a fixing property and a durability. Therefore, to fulfill these demands, there is still a need to develop a toner having various internal additives adequately dispersed therein, distributed through the use of an agglomerating agent that is high in a cohesive force in the an agglomeration operation of preparing the polymerized toner, is resistant to an external environment, and is safe to humans.